Study On 15CrMo Surface Modification By Micro-beam Plasma Arc

Long-term running with high rotary speed under the condition of high temperature and pressure, the axis of gas turbine rotor might be worn-out that result in power equipment be incapable of work normally, even out-of-service. But it is too expensive for us to replace the old axis with a new one. So it is very necessary and beneficial to repair the wore-out axis surface in time and high efficiency, high quality.Considering the narrow and shallow defects of worn-out axis, Micro-beam plasma arc was introduced as heat source to study surface modification of 15CrMo. By changing parameters such as scanning current and speed, the dimension of melting zone, microstructure and performance were researched. Microstructure and performance of Surface cladding nickel base alloy were studied. Finally, the method of surface cladding by MBPA was compared with the coating layer by oxy-acetylene flame spraying.The experimental results of surface cladding by MBPA indicate that the width and depth of melting zone increase when scanning current change from 10A to 30A. The microstructure of melting zone is lath martensite, accordingly, their grain become gradually coarse and its micro-hardness decrease. In the range of scanning velocity 4mm/s to 20mm/s, the width and depth of melting zone decline gradually. The microstructure of coating layer was lath martensite. Accordingly, its grain became fine and micro-hardness increased continually. Melting by MBPA could make the surface strengthen, its micro-hardness reached to 400-520 HV, which is as twice as the base metal. Its wear-resistance and service life are improved greatly. The results of electrochemical corrosion experiment illustrate that the corrosion-resistance...